Questioning the low fat-high carbohydrate diet - Shorts

Townsend Letter for Doctors and Patients, August-Sept, 2003 by Jule Klotter

A variety of low-carbohydrate diets (which allow more protein and fat) are now being tested. A six-month study of Robert Atkins' low-carb diet found that overweight participants on the Atkins diet lost more pounds than those on the American Heart Association's low-fat diet. Those on the Atkins diet also showed an increase in beneficial HDL cholesterol (11%) and a 49% decrease in triglyceride levels. Those on the AHA diet showed no change in HDL levels and only a 22% drop in triglyceride levels. The Atkins diet puts stringent limits on carbohydrate consumption but allows patients to eat protein and saturated fats without limit.

The results of this and other small studies have encouraged the National Institutes of Health to fund larger, long-term studies that compare popular diets, according to a New York Times article (July 7, 2002) by Gary Taubes. Dr. Gary Foster of the University of Pennsylvania and colleagues have received NIH funding to do a five-year study of the effects of the Atkins diet on 360 people. Harvard endocrinologist David Ludwig has also received money from the NIH to test his low-glycemic-index diet. He has been prescribing a low-glycemic diet to children and adolescents for five years. Instead of banning carbohydrates from the diet, he tells patients to replace refined carbohydrates and starches that cause the blood sugar level to rise quickly (high glycemic) with vegetables, fruits, and legumes that do not (low glycemic). Again, carbohydrates and their effect on blood sugar are the focus rather than dietary fat.

The idea that dietary fat, particularly saturated fat, is bad for health arose in the 1950s. In January 1977, a US Senate committee latched on to that hypothesis and recommended that Americans lower their fat

intake in its "Dietary Goals for the United States." Over seven years later, the National Institutes of Health made the recommendation official, and the food industry began producing and advertising an array of reduced-and low-fat products. In order to give their low-fat products a good taste, food manufacturers used more sugar and high-fructose corn syrup. People also began avoiding animal protein foods, such as meat, eggs, and dairy products, because of their high fat content. The result was a diet low in fats but high in carbohydrates.

According to Gary Taubes, the hypothesis that dietary fat raises cholesterol levels and causes heart disease has not been established. He says that the NIH has sponsored five large studies that failed to establish a clear link between dietary fat and heart disease. Moreover, the move to a low-fat diet has failed to produce the expected improvements in health. Epidemiologists report a steep rise in obesity, beginning in the 1980s and continuing through the 1990s. The incidence of Type II diabetes is also growing, and the illness is now showing up in adolescents. USDA agricultural economist Judith Putnam says that annual consumption of caloric sweeteners has increased by 30 pounds per person since the late 1970s, and people are eating almost 400 more calories per day since the government began recommending a low-fat diet. Fat and protein help the body feel satiety and, thereby, protect against overeating.

A growing number of scientists and practitioners are saying that carbohydrates, not fats, are the real health threat. The low-fat dietary advice was advanced by doctors who were looking at cholesterol levels and heart disease. Yet, researchers had shown by the late 1960s that high tryglyceride levels correspond to heart disease at least as often as high LDL cholesterol levels. Endocrinologists now know that a diet that is high in certain carbohydrates will raise triglyceride levels and lower HDL cholesterol in many people. Also, refined carbohydrates, such as quickly-digested grains (e.g., pasta, refined rice, bread), or those with a high sugar content raise blood sugar levels and increase insulin production. Long-term damage results if the body produces too much insulin. The damage, which endocrinologist Gerry Reaven dubbed Syndrome X, can take the form of heart disease, obesity, and Type II diabetes.

Taubes, Gary. What if It's All Been a Big Fat Lie? www.nytimes.com/2002/07/07/magazine/07FAT.html

Associated Press. Atkins diet beats low-fat fare. 18 November 2002. www.msnbc.com/news/836726asp?cp1=1#BODY